U.S. patent number 8,903,045 [Application Number 13/446,521] was granted by the patent office on 2014-12-02 for backscatter system with variable size of detector array.
This patent grant is currently assigned to American Science and Engineering, Inc.. The grantee listed for this patent is William Randall Cason, Jeffrey R. Schubert. Invention is credited to William Randall Cason, Jeffrey R. Schubert.
United States Patent |
8,903,045 |
Schubert , et al. |
December 2, 2014 |
Backscatter system with variable size of detector array
Abstract
A variable-geometry backscatter inspection system has a
radiation detector array including one or more backscatter
radiation detectors. The position of a second backscatter radiation
detector is variable with respect to the position of a first
backscatter radiation detector, so that the size of the detector
array may be varied by moving the second radiation detector into or
out of a predefined alignment with the first radiation detector.
The system may include a movable base, and at least one of the
detectors is movable with respect to the base. Methods of
inspecting an object include forming a detector array by moving a
second radiation detector into a predefined alignment with a first
radiation detector, illuminating the object with a pencil beam of
penetrating radiation, and detecting backscattered radiation with
the detector array.
Inventors: |
Schubert; Jeffrey R.
(Somerville, MA), Cason; William Randall (Danvers, MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Schubert; Jeffrey R.
Cason; William Randall |
Somerville
Danvers |
MA
MA |
US
US |
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|
Assignee: |
American Science and Engineering,
Inc. (Billerica, MA)
|
Family
ID: |
47006377 |
Appl.
No.: |
13/446,521 |
Filed: |
April 13, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120263276 A1 |
Oct 18, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61475994 |
Apr 15, 2011 |
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Current U.S.
Class: |
378/86; 378/7;
378/70 |
Current CPC
Class: |
G01N
23/203 (20130101) |
Current International
Class: |
G01N
23/203 (20060101); G01N 23/201 (20060101) |
Field of
Search: |
;378/58,70,86-89,196-198
;250/370.08,370.09 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Authorized Officer: Jihun Cho Notification of Transmittal of the
International Search Report and the Written Opinion of the
International Searching Authority, or the Declaration,
PCT/US2012/033585; Date of Mailing: Nov. 29, 2012, 11 pages. cited
by applicant.
|
Primary Examiner: Souw; Bernard E
Attorney, Agent or Firm: Sunstein Kann Murphy & Timbers
LLP
Parent Case Text
TECHNICAL FIELD
This patent application claims priority from provisional U.S.
patent application No. 61/475,994, filed Apr. 15, 2011, entitled,
"Backscatter System with Variable Size Detector Array" and naming
Jeffrey R. Schubert and William Randall Cason as inventors, the
disclosure of which is incorporated herein, in its entirety, by
reference.
Claims
What is claimed is:
1. A variable geometry backscatter inspection system for inspecting
a surface of an object, the system comprising: a conveyance
configured to move along a line of travel; a source of a pencil
beam of penetrating radiation, the source coupled to the conveyance
and having an axis of emission; a variable geometry detector array,
the array comprising: a first detector coupled to the conveyance
and having a first alignment vector, the first alignment vector
parallel to the line of travel; a second detector movably coupled
to the conveyance and having a second alignment vector, the second
detector movable between a first position and a second position,
wherein the second alignment vector is parallel to the line of
travel in the first position; such that the array presents a first
solid angle when viewed from a point on the line of travel when the
second detector is in the first position, and a smaller solid angle
when the second detector is in the second position.
2. The variable geometry backscatter inspection system of claim 1,
wherein the second detector movably coupled to the conveyance by a
movable member.
3. The variable geometry backscatter inspection system of claim 1,
wherein the movable member comprises an arm, the arm comprising: a
first end rotatably coupled to the conveyance; and a second end
coupled to the second detector.
4. The variable geometry backscatter inspection system of claim 1,
wherein the second detector comprises a first unit and a second
unit, the second unit foldable to face the first unit.
5. The variable geometry backscatter inspection system of claim 2,
wherein the movable member comprises: a detector frame defining the
second alignment vector parallel to the first alignment vector, and
movable with respect to the conveyance such that the second
alignment vector remains parallel to the first alignment vector in
both the first and second position.
6. The variable geometry backscatter inspection system of claim 5,
wherein the detector frame is adapted for motion parallel to a
surface on which the conveyance is located.
7. The variable geometry backscatter inspection system of claim 5,
wherein the detector frame is adapted for motion perpendicular to a
surface on which the conveyance is located.
8. The variable geometry backscatter inspection system of claim 5,
wherein the detector frame is adapted for motion diagonally with
respect to a surface on which the conveyance is located.
9. A variable geometry backscatter inspection system for inspecting
a surface of an object, the system comprising: a conveyance; a
source of a pencil beam of penetrating radiation, the source
coupled to the conveyance; a primary detector coupled to the
conveyance, the primary detector having a first location relative
to the radiation source and a first alignment vector; a movable
member movably coupled to the conveyance; and a secondary detector
coupled to the movable member, the secondary detector having a
second alignment vector, such that the alignment vector of the
secondary detector is configured for reorientation with respect to
the alignment vector of the primary detector in such a manner that
the sensitivity of the system to radiation scattered from the
object is substantially maximized when the first and second
alignment vectors are substantially parallel.
10. The variable geometry backscatter inspection system of claim 9,
wherein the movable member comprises an arm, the arm comprising: a
first end rotatably coupled to the conveyance; and a second end
coupled to the secondary detector; such that the arm rotatable
between an open position in which the second alignment vector is
parallel to the first alignment vector, and a retracted position in
which the second alignment vector is not parallel to the first
alignment vector.
11. The variable geometry backscatter inspection system of claim
10, wherein the second alignment vector is perpendicular to the
first alignment vector when the second end is in the retracted
position.
12. The variable geometry backscatter inspection system of claim 10
wherein the secondary detector comprises a first unit and a second
unit, the second unit foldable to face the first unit.
13. The variable geometry backscatter inspection system of claim 9,
wherein the movable member comprises: a detector frame defining a
secondary alignment vector parallel to the first alignment vector
and movable with respect to the conveyance such that the secondary
alignment vector remains parallel to the first alignment
vector.
14. The variable geometry backscatter inspection system of claim
13, wherein the detector frame is adapted for motion parallel to a
surface on which the conveyance is located.
15. The variable geometry backscatter inspection system of claim
13, wherein the detector frame is adapted for motion perpendicular
to a surface on which the conveyance is located.
16. The variable geometry backscatter inspection system of claim
13, wherein the detector frame is adapted for motion diagonally
with respect to a surface on which the conveyance is located.
17. A method for inspecting an object with backscatter radiation,
the method comprising: providing a conveyance comprising a source
of a pencil beam of penetrating radiation; providing a first
detector of backscatter radiation, the first detector having a
fixed position relative to the conveyance, and the first detector
having a first alignment vector; providing a second detector of
backscatter radiation, the second detector movably coupled to the
conveyance, and the second detector having a second alignment
vector; orienting the second detector such that the second
alignment vector intersects the first alignment vector;
illuminating the object with a pencil beam of radiation from the
source; detecting radiation scattered by the source with the first
detector and the second detector; generating a first image of the
object using data representing the radiation scattered by the
source and detected by the first detector; and generating a second
image of the object using data representing the radiation scattered
by the source and the second detector.
18. The method of claim 17, further comprising producing a compound
image by combining data from the first image with data from the
second image.
19. The method of claim 18, wherein producing a compound image by
combining data from the first image with data from the second image
includes producing a dynamically variable image by adjusting the
proportion of the first image and the proportion of second image
combined to produce the compound image.
20. The method of claim 17, wherein orienting the second detector
such that the second alignment vector intersects the first
alignment vector comprises orienting the second detector such that
the second alignment vector intersects the first alignment vector
the angle at a right angle.
Description
TECHNICAL FIELD
The present invention relates to detector arrays, and more
particularly to arrays for detecting backscattered penetrating
radiation such as x-rays.
BACKGROUND ART
It is known in the prior art to inspect an object by illuminating
it with penetrating radiation. Some of the radiation may pass
through the object, and some may be absorbed or deflected by the
object. Some of the illuminating radiation, however, will be
scattered in all directions, such as back in the general direction
from which it came, in which case the scattered radiation may be
referred to as backscatter radiation. Such scattered radiation may
pass into a detector (which may be referred to, herein, as a
"scatter detector," and some portion of that scattered radiation
will be detected by the detector.
Existing systems for inspection of objects, for security
applications, for example, employ scatter detectors that are fixed
in position relative to the beam of illuminating radiation, or
that, upon reorientation, subtend substantially the same solid
angle with respect to the inspected object as before reorientation.
One such system with reconfigurable scatter detectors is shown in
FIGS. 5A and 5B of U.S. Pat. No. 5,764,683. Such inspection
systems, however, are designed for inspection, at specified range,
on the order of a meter, of a particular class of objects (namely,
cars and trucks), which are inspected at a substantially fixed
distance with respect to the inspection system. Such inspection
systems cannot provide for substantial variation in the footprint
of the detector array when called upon for inspection in
particularly close quarters, or so as to accommodate substantial
variation in the distance between the inspection system and the
inspected object. The latter might be necessary in a field
deployment, where the inspected object may be disposed at a
substantial distance from the inspection system.
SUMMARY OF THE EMBODIMENTS
In a first embodiment a variable geometry backscatter inspection
system for inspecting a surface of an object, the system includes a
conveyance configured to move along a line of travel; a source of a
pencil beam of penetrating radiation, the source coupled to the
conveyance and having an axis of emission; a variable geometry
detector array that includes a first detector coupled to the
conveyance and having a first alignment vector, the first alignment
vector parallel to the line of travel, and a second detector
movably coupled to the conveyance and having a second alignment
vector, the second detector movable between a first position and a
second position, wherein the second alignment vector is parallel to
the line of travel in the first position, such that the array
presents a first solid angle when viewed from a point on the line
of travel when the second detector is in the first position, and a
smaller solid angle when the second detector is in the second
position.
In some embodiments, the second detector movably coupled to the
conveyance by a movable member. In some embodiments the movable
member includes and arm having a first end rotatably coupled to the
conveyance, and a second end coupled to the second detector.
In some embodiments, the second detector includes a first unit and
a second unit, the second unit foldable to face the first unit.
In some embodiments, wherein the movable member includes a detector
frame defining the second alignment vector parallel to the first
alignment vector, and movable with respect to the conveyance such
that the second alignment vector remains parallel to the first
alignment vector in both the first and second position. In some
embodiments, the detector frame is adapted for motion parallel to a
surface on which the conveyance is located, while in some
embodiments the detector frame is adapted for motion perpendicular
to a surface on which the conveyance is located, and in some
embodiments the detector frame is adapted for motion diagonally
with respect to a surface on which the conveyance is located.
In another embodiment, a variable geometry backscatter inspection
system for inspecting a surface of an object includes a conveyance;
a source of a pencil beam of penetrating radiation, the source
coupled to the conveyance; a primary detector coupled to the
conveyance, the primary detector having a first location relative
to the radiation source and a first alignment vector; a movable
member movably coupled to the conveyance; and a secondary detector
coupled to the movable member, the secondary detector having a
second alignment vector, such that the alignment vector of the
secondary detector is configured for reorientation with respect to
the alignment vector of the primary detector in such a manner that
the sensitivity of the system to radiation scattered from the
object is substantially maximized when the first and second
alignment vectors are substantially parallel.
In some embodiments, the movable member includes an arm, and the
arm includes a first end rotatably coupled to the conveyance, and a
second end coupled to the secondary detector, such that the arm
rotatable between an open position in which the second alignment
vector is parallel to the first alignment vector, and a retracted
position in which the second alignment vector is not parallel to
the first alignment vector.
In some embodiments, the second alignment vector is perpendicular
to the first alignment vector when the second end is in the
retracted position.
In some embodiments, the secondary detector includes a first unit
and a second unit, the second unit foldable to face the first
unit.
In some embodiments, the movable member includes a detector frame
defining a secondary alignment vector parallel to the first
alignment vector and movable with respect to the conveyance such
that the secondary alignment vector remains parallel to the first
alignment vector.
In some embodiments, the detector frame is adapted for motion
parallel to a surface on which the conveyance is located, and in
some embodiments, the detector frame is adapted for motion
perpendicular to a surface on which the conveyance is located, and
in some embodiments, the detector frame is adapted for motion
diagonally with respect to a surface on which the conveyance is
located.
In another embodiment, a method for inspecting an object with
backscatter radiation, the method includes the steps of providing a
conveyance comprising a source of a pencil beam of penetrating
radiation; providing a first detector of backscatter radiation, the
first detector having a fixed position relative to the conveyance,
and the first detector having a first alignment vector; providing a
second detector of backscatter radiation, the second detector
movably coupled to the conveyance, and the second detector having a
second alignment vector; orienting the second detector such that
the second alignment vector intersects the first alignment vector;
illuminating the object with a pencil beam of radiation from the
source; detecting radiation scattered by the source with the first
detector and the second detector; generating a first image of the
object using data representing the radiation scattered by the
source and detected by the first detector; and generating a second
image of the object using data representing the radiation scattered
by the source and the second detector.
In some embodiments, the method also includes producing a compound
image by combining data from the first image with data from the
second image.
In some embodiments, the step of producing a compound image by
combining data from the first image with data from the second image
includes producing a dynamically variable image by adjusting the
proportion of the first image and the proportion of second image
combined to produce the compound image.
In some embodiments, the step of orienting the second detector such
that the second alignment vector intersects the first alignment
vector comprises orienting the second detector such that the second
alignment vector intersects the first alignment vector the angle at
a right angle.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing features of embodiments will be more readily
understood by reference to the following detailed description,
taken with reference to the accompanying drawings, in which:
FIG. 1 schematically illustrates two variable geometry backscatter
inspection systems positioned adjacent to an airplane;
FIG. 2 schematically illustrates a radiation detector and an
alignment vector;
FIG. 3 schematically illustrates an embodiment of a variable
geometry backscatter inspection system;
FIG. 4A and FIG. 4B schematically illustrate embodiments of
variable geometry backscatter inspection systems;
FIG. 5 schematically illustrates another embodiment of a variable
geometry backscatter inspection system;
FIG. 6 schematically illustrates another embodiment of a variable
geometry backscatter inspection system;
FIG. 7A and FIG. 7B schematically illustrate embodiments of
variable geometry backscatter inspection systems;
FIG. 8 schematically illustrates another embodiment of a variable
geometry backscatter inspection system;
FIG. 9 schematically illustrates another embodiment of a variable
geometry backscatter inspection system;
FIG. 10 schematically illustrates another embodiment of a variable
geometry backscatter inspection system;
FIGS. 11A-11D are digital images of an object, and various images
of that object produced by an embodiment of a variable geometry
backscatter inspection system;
FIG. 12 is a flowchart that schematically illustrates a method of
inspecting an object.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
In accordance with illustrative embodiments, an array of detectors
is configured to present a detector of backscatter radiation with
variable geometry. To that end, a detector array has a number of
detectors of backscattered radiation ("detectors") that can change
positions or orientations with respect to one another.
FIG. 1 schematically illustrates two backscatter detector systems
101 and 102 adjacent to a small aircraft 103. Each of the
backscatter detector systems 101 and 102 includes a source of
penetrating radiation 104, 105 respective pointed at the aircraft
103. Each source 104, 105, may produce a narrow beam of penetrating
radiation, which may be known as a pencil beam of penetrating
radiation. In fact, systems 101 and 102 are identical, but are
configured differently in FIG. 1.
System 102 will be described in detail below, with the
understanding that system 101 has the same components. As shown in
FIG. 1, the ability to configure the backscatter detector systems
101 and 102 allows system 102 to be configured so that its detector
array presents a smaller profile than the array in system 101. As
such, system 102 is able to move closer to the plane 103 in the
tight space between the wing 108 and fuselage 109. This ability
extends the scope of useful applications for the system 102.
In operation of system 102, the source 104 illuminates the aircraft
103 with penetrating radiation, and a portion of that illuminating
radiation (the "scattered" or "backscattered" radiation) is
scattered back in the general direction of the source. Unlike the
pencil beam of penetrating radiation, the scattered radiation is
omnidirectional. As such, some of the scattered radiation passes
into the detectors 106 and 107, which together form detector array
113. Some of that backscattered radiation may pass through the
detectors 106 and 107 undetected, while some of the backscattered
radiation will be detected by those detectors.
Generally, the greater the solid angle of the detector or detectors
as measured from a point of scatter, the more likely that the
backscattered radiation will be detected. Thus, the dimensions of
the detector (or an array of detectors) may influence a system's
sensitivity.
Accordingly, in describing various embodiments and in any claims
appended hereto, the following definition may be employed: the term
"alignment vector," when used with respect to a detector of
scattered radiation, shall refer to a direction defined by a linear
locus of points extending outward from the detector, with respect
to which the solid angle subtended by the volume of the detector as
seen from an observation point on the linear locus of points
exceeds the solid angle as seen from any other point in a plane,
which plane is transverse to the vector at the observation
point.
In various embodiments described herein, the alignment vectors of
various radiation detectors are parallel to the alignment vectors
of other detectors, and/or parallel to the transmission axis of
pencil beam of penetrating radiation. While such an orientation may
maximize the total sensitivity of the respective arrays, this is
not a required limitation. For example, if less than 100 percent
sensitivity from a given detector within an array of detectors is
sufficient for a given application, the respective alignment
vectors may be oriented at an angle greater than zero (i.e., the
vectors are not parallel). Therefore, in some embodiments an
"alignment vector" can refer to a line that intersects a locus of
points as described above at a fixed, pre-determined angle.
For example, a cross-section 200 of a detector of penetrating
radiation 201 is schematically illustrated in FIG. 2. Point P1 is
in the plane of the cross-section and on a locus of points 202
extending outward from the detector 201. Radiation scattering
(e.g., backscattering) from point P1 in the plane of the
cross-section 200 will reach the detector 201 if the backscattered
radiation is within the 53 degree arc A1. In other words, all
radiation within the plane of the cross-section 200 and within the
arc A1 will pass into the detector 201, and thereby provide an
opportunity for detector 201 to detect it. In this sense, point P1
may be considered a point source of radiation, even though in fact
it is a point from which impinging radiation is scattered. As such,
it is not necessary to specify the ultimate source of the
penetrating radiation.
In contrast, radiation scattering from point P2, which is on a
plane 203 transverse to the locus of points 202 at point P1 (in
FIG. 2, the plane is perpendicular to the cross-section, and
therefore appears as a line), will only reach detector 201 if it
scatters within the 45 degree arc A2.
Thus, the solid angle subtended by the volume of the detector 201
as seen from point P1 is larger than the solid angle subtended by
the volume of the detector 201 as seen from point P2.
In fact, of all the points in plane 203, none will present a solid
angle subtended by the volume of the detector 201 larger than the
solid angle presented from point P1. As such, the locus of points
202 is the alignment vector in accordance with the foregoing
definition.
One embodiment of a backscatter detector system 300 is
schematically illustrated in FIG. 3, and includes a base, or
conveyance 301, which supports the other elements of the system. In
this figure, the system 300 is resting on the ground and viewed
from a point above the system looking down.
The conveyance 301 may be adapted for ease of mobility, and to that
end may have wheels or tracks to engage the surface on which the
system is placed. Alternately, the conveyance 301 may be a platform
coupled to a base, such that the platform can move independently of
the base.
The system 300 also has an X-ray source 302, which may produce a
pencil-beam of penetrating radiation as described above. In this
embodiment, the X-ray source 302 is coupled to the conveyance 301
so that the X-ray source bears a fixed spatial relationship to the
conveyance 301. In operation, therefore, illuminating an object
involves moving the conveyance 301 so that the X-ray source 302
points in the direction of the object.
The system 300 also includes two detectors, 303 and 304, each of
which has an associated alignment vector. These detectors, 303 and
304, which may be known as the "primary detectors," are coupled to
the conveyance 301 such that they each bear a fixed spatial
relationship to the conveyance 301. Together, the primary detectors
303 and 304 form an array of detectors.
In operation, some of the radiation produced by X-ray source 302
will be scattered by the illuminated object back in the general
direction of the detectors 303 and 304, and will consequently be
detected by the detectors.
In some embodiments, data representing the detected backscatter
radiation is then provided to a computer (not shown), and processed
using specialized software to produce an image of the object. To
that end, the system may have one or more data communication
channels to convey digitized data to a memory or computer
processor. Detected radiation may be digitized and transmitted to a
microprocessor or using a data communication channel.
The sensitivity of the system 300 will be defined, at least in
part, by the detectors 303 and 304. However, some of the
backscattered radiation will escape detection by detectors 303 and
304 because it passes wide of those detectors. In other words,
radiation backscattering from a point on the object may scatter at
an angle outside the solid angle presented by the volume of the
detectors 303 and 304 as seen from that point. As such, the
sensitivity of the system 300 may be enhanced by controllably
adding additional detectors to increase the solid angle of the
array of detectors as seen from the point of backscatter. Such a
system may be known as a variable geometry backscatter detection
system.
To that end, the system 300 has two additional detectors, 305 and
306. These may be known as "secondary" detectors or "auxiliary"
detectors. In this embodiment, the secondary detectors 305 and 306
are movably coupled to the conveyance 301 by respective arms 307
and 308. Thus, although the secondary detectors 305 and 306 are
coupled to the conveyance 301, they do not bear a fixed special
relationship to the conveyance because their position is variable.
Secondary detector 305, arm 307, pivot joint 309, and pivot point
310 will be described below, with the understanding that secondary
detector 306, arm 308, pivot joint 311 and pivot point 312 operate
in the same way.
Arm 307 is coupled to the conveyance 301 by a pivot joint 309 that
allows the arm 307 to rotate (or swing) about pivot point 310. In
this way, the position of detector 305 may be adjusted so that it
is facing the object. In some orientations, the alignment vector of
secondary detector 305 may be parallel to the alignment vectors of
the primary detectors 303 and 304. In such an "open" configuration
(i.e., when the alignment vectors of the primary and secondary
detector are substantially parallel), the system 300 will detect
more of the backscattered radiation than it would with the primary
detectors 303 and 304 alone. Stated alternately, the sensitivity of
the system 300 to radiation scattered from the object is
substantially increased when the first and second alignment vectors
are substantially parallel. In some embodiments, the position of
the detectors may be adjusted so that the alignment vector of each
detector includes the point of scatter.
The movable arm 307 also allows the secondary detector 305 to be
refracted to a position in which its alignment vector is not
parallel to that of the primary detectors 303 and 304. In some
embodiments, the alignment vector of secondary detector 305 may
form an angle of about eighty or even ninety degrees with the
alignment vector of primary detector 303. In such a "retracted"
configuration, the system 300 will detect less of the backscattered
radiation than it would with the secondary detector 305 in an
"open" configuration. Indeed, in a "retracted" configuration, some
or all of the backscattered radiation may be blocked or absorbed by
other elements of the system 300, such as primary detectors 303 or
304, or the source 302.
In some embodiments, the alignment vectors of the secondary
detectors may be perpendicular to the alignment vectors of the
primary detectors when retracted. In such a configuration, which is
illustrated by dashed arms (307' and 308') and detectors (305' and
306') in FIG. 3 and which may be known as a "closed" configuration,
the sensitivity of the array is reduced (because the array itself
is reduced) as compared to the open position described above, but
the system is also is more compact. When a secondary detector (305
or 306) is retracted from its fully open position, a data
communication channel coupled to that detector may disengage from
that detector. For example, the data communication channel could be
physically de-coupled from the detector, or it could be
electrically turned off or its communications suspended.
A system in a closed configuration may be easier to move, and may
also allow the system to be positioned closer to an object in tight
quarters than the same system in an open configuration. For
example, the corners 110 at the intersection of the wing 108 and
fuselage 109 of the aircraft 103 schematically illustrated in FIG.
1 presents an irregular contour to the systems 101 and 102. As
shown, system 102 is positioned closer to the aircraft 103 than
system 101. As such, because the array of detectors 106, 107 of
system 102 has been configured to be smaller than the array as
configured in system 101, system 102 is able to access portions of
the aircraft 103 that may not be as readily accessible to system
101 which is configured in the open position. In fact, because
system 102, as configure, can get closer to the corner 110, the
detectors 106, 107 of system 102 may present a large solid angle,
as viewed from the corner 110, than could the array of detectors on
system 101, because the array of detectors 101 is too wide to
maneuver close such a corner 110. In other words, in some
applications, a smaller detector array may present a larger solid
angle to a point of interrogation than a larger array.
On the other hand, the detector array of system 101 may present a
solid angle (from a point on the airplane 103) similar to that
presented to system 102, even though system 101 is further away
from the airplane. As such, system 101 may be able to detect an
equal amount of backscatter radiation as a system with a smaller
array, but without having to be as close to the object.
Additional embodiments are schematically illustrated in FIGS. 4A
and 4B. In FIG. 4A, the system 400 is resting on the ground and
viewed from a point above the system 400 looking down. Secondary
detectors 401, 402, 403 and 404, each have an alignment vector, and
each is movably coupled to conveyance 405 at pivot points 406 and
407 on the sides 408 and 409 of the conveyance. Pairs of detectors,
such as detectors 401 and 402, may be thought of as sub-arrays, and
a sub-array may have an alignment vector. In one configuration, the
detector array of system 400 may be defined by moving one of the
detectors 401, 402 (or a sub-array of detectors) to a position in
which its alignment vector is parallel to the alignment vectors of
primary detectors 410 and 411. Alternately, the size of the
detector array may be reduced by moving one of the secondary
detectors 401, 402 to a position in which its alignment vector is
other than parallel to the alignment vector of primary detectors
410 and 411.
System 420 is schematically illustrated in FIG. 4B as resting on
the ground and viewed in side profile. System 420 includes a
secondary detector 421 pivotably attached to the top 422 of the
conveyance. The secondary detector 421 is illustrated as a single
unit, but could also be a sub-array of several detectors. In one
configuration, the detector array of system 420 may be defined by
moving the detector 421 into a position in which its alignment
vector is parallel to the alignment vector of primary detector 424.
Alternately, the size of the detector array may be reduced by
moving the secondary detector 421 to a position in which its
alignment vector is other than parallel to the alignment vector of
primary detector 424.
In another embodiment 500, sub-arrays may themselves be foldable,
as schematically illustrated in FIG. 5. Sub-array 501 has an inner
portion 502 (detectors 507 and 508) nearest the conveyance 504, and
an outer portion 503 (detectors 505 and 506). In this embodiment,
each portion has two detectors, and each detector has an associate
alignment vector.
In an open position, the alignment vectors of detectors 505-508 are
parallel to each other, and parallel to the alignment vectors of
primary detectors 509 and 510. In a closed position, the alignment
vectors of detectors 505-508 are not parallel to the alignment
vectors of primary detectors 509 and 510. Also, in the closed
position the detectors face each other in what may be termed a
"clamshell" position, resulting a compact orientation. In this
configuration, the alignment vectors of the secondary detectors 505
and 506 may be parallel to each other, but in opposing directions
to the alignment vectors of detectors 507 and 508.
An embodiment 600 combining swinging arms 601, 602 (similar to
those in FIG. 3) and foldable sub-arrays 603, 604 (similar to those
in FIG. 5) is schematically illustrated in FIG. 6.
Other embodiments are schematically illustrated in FIG. 7A and FIG.
7B. In each case, secondary detector arrays are coupled to the back
of a conveyance positioned on the ground.
In FIG. 7A, the system 700 is viewed from above. In this
embodiment, one (701) or more (702) secondary arrays may be secured
to a framework ("frame" 703, 704) that is movably coupled to a
conveyance 705. By moving the frame (e.g., 703), the detectors
702A, 702B may move relative to the conveyance to be in a "closed"
position (top illustration) or an "open position" (bottom
illustration), or in positioned in-between. To move from the closed
position to the open position, the one or more secondary array(s)
slide outwards, parallel to the ground. In an alternate embodiment,
also illustrated by FIG. 7A, the frame and secondary arrays may
move diagonally--neither parallel to nor perpendicular to the
ground.
At all times, the alignment vectors of the detectors 701A, 701B,
702A and 702B of the secondary array(s) are parallel to the
alignment vectors of the primary detectors 706A and 706B, but the
effective size of the system's detector array is determined by the
location of the secondary arrays. Even though the respective
alignment vectors of the primary and secondary detectors are
parallel to each other irrespective of the location of the
secondary detectors, the sensitivity of the system's detector array
is likely to be greater when the secondary detector arrays are in
the open position because in any other position the conveyance
itself is likely to secondarily scatter or absorb some portion of
the backscatter radiation that might otherwise reach the secondary
detectors.
In FIG. 7B, the system 720 is viewed in side profile, and the
secondary array 721 slides upwards (i.e., perpendicular to the
ground) from a "closed" position (bottom illustration) to an "open"
position (top illustration).
An omnidirectional forklift 801 is the conveyance in the embodiment
800 schematically illustrated in FIG. 8. The forklift 801 has a
lifting platform 802 with a lifting surface 803, and may move
forward and backward like a conventional forklift, but the forklift
801 can also move sideways. For example, for scanning along a large
object, the forklift 801 can move sideways while the radiation
source 804 and detector array 807 face the object.
The detector array 807 of system 800 includes primary detectors
805, as well as secondary detector arrays 806A and 806B. The
secondary detectors 806A and 806B are movably coupled to the
conveyance 801 so that their position or orientation relative to
the primary detectors 805 is variable. The secondary detector
arrays 806A and 806B may be implemented in ways described above,
for example.
In addition, the detector array 807, along with a radiation source
804 capable of projecting a pencil beam of penetrating radiation
along a transmission axis, may be rotatably attached to the
forklift's lifting platform 802, such that they may rotate around
an axis normal to the lifting surface 803 of the lifting platform
802, while the detectors 805, 806A and 806B, and radiation source
804, maintain a fixed spatial relationship with respect to each
other.
As such, the transmission axis and the alignment axes of the
detectors 805, 806A and 806B may be rotated relative to the lifting
platform 802, so as to allow them to be oriented or re-oriented
with respect to an object without having to move the entire system
800. In this embodiment, the beam plane/transmission axis may
rotate nearly 270 degrees. For example, the radiation source 804
and detector array 807 could be rotated during a scanning operation
without having to move the forklift 801.
Yet another embodiment 900 is schematically illustrated in FIG. 9.
System 900 includes a turntable 901 supporting a radiation source
902 that produces a pencil beam of penetrating radiation along a
transmission axis 903, as well as a set of primary detectors 904A,
904B, 904C and 904D. Each of the primary detectors 904A-904D has an
alignment vector, and together they form a primary array 907 that
also has an alignment vector.
The radiation source 902 and primary array 907 have a fixed
position relative to each other, but may rotate relative the
conveyance 905 around an axis normal to the surface of the
turntable 901. Some embodiments include a lifting mechanism 906,
such as a scissor lift, between the conveyance 905 and the
turntable 901, to enable the turntable 901 to elevate with respect
to the conveyance 905.
The system 900 also has a secondary array 908 including two
secondary detectors 909A and 909B. Each of the secondary detectors
909A and 909B individually, and the secondary array 908, has an
alignment vector. The secondary detectors 909A and 909B are coupled
to the conveyance 905 and bear a fixed spatial relationship to the
conveyance 905.
In operation, primary array 907 may be rotated such that its
alignment vector is parallel to the alignment vector of the
secondary array 908. As such, the primary and secondary arrays may
form a larger, system array. The solid angle of the combined arrays
as seen from a point of backscatter is larger than the solid angle
presented by the primary array 907 alone, so that the system array
may be formed by rotating the primary array 907 so that its
alignment vector is parallel to the alignment vector of the
secondary array 908.
Another embodiment 1000 is schematically illustrated in FIG. 10,
and includes a vehicle (or conveyance) 1001 having a first detector
1002 and an x-ray source 1003 mounted within the interior of the
vehicle 1000. In this location, the first detector 1002 is
configured to detect backscatter radiation from a target automobile
1004.
In in this embodiment, vehicle 1000 also has a second detector 1005
disposed on the roof of the vehicle 1000. The second detector 1005
may be protected by a weather-tight housing 1007.
The second detector 1005 may be optionally and controllably
oriented so as become part of a detector array 1006, along with the
first detector 1002, or moved into a stowed position 1005S, as
indicated by the dashed outline of detector 1005. The second
detector may be referred to as a "top-down detector," "wing
detector" or "awning detector."
The second detector may be oriented in a variety of positions with
respect to the vehicle and/or with respect to the first detector.
In some embodiments, the second detector 1005 is slideably mounted
to the vehicle, so that the second detector 1005 may be oriented
from a stowed position 1005S to an awning position 1005A by sliding
the second detector.
In other embodiments, the second detector 1005 may be pivotally
mounted to the vehicle 1000, such that the second detector 1005 may
be rotated into a variety of positions. For example, in such
embodiments, the second detector 1005 may be rotated into a
vertical position 1005V as indicated by the double-headed arrow
1008, such that its alignment vector is parallel to the alignment
vector of the first detector 1003. In some embodiments, the face
1005F of the second detector may be coplanar with the face 1003F of
the first detector. Second detector 1005 could also be rotated into
stowed position 1005S.
Alternately, the second detector 1005 may be rotated into an awning
position 1005A, such that its alignment vector is perpendicular,
and may even intersect, the alignment vector of the first detector
1003. In addition, the second detector may be rotated to any
desired angle between the awning position 1005A and stowed position
1005S.
As such, the second detector allows an operator of the system to
adjust both the size and shape of the detector array, depending for
example on both the size of the target vehicle and the available
height clearance, and also depending on the distance between the
array and the target.
Deployed horizontally as schematically illustrated as location
1005A in FIG. 10, the second detector offers several advantages.
For example, the overall solid angle of the detector array 1006 is
increased over the solid angle of the first detector alone (by
roughly a factor of two, for the geometry shown in FIG. 10) which
increases the flux (roughly in proportion to the solid angle) and
the overall signal-to-noise ratio of an image produced from
detected backscatter radiation.
In addition, penetration is improved beyond what would be expected
from the improved signal-to-noise ratio alone. X-rays that scatter
at angles closer to 90.degree. than to 180.degree. (i.e. X-rays
that are more side-scatter than backscatter) will have higher
energies. As such, in connection with an inspection of car 1004,
for example, the scattered radiation is better able to escape from
the metal and glass enclosure of the car 1004. The roof and trunk
lid of a car are generally made of thinner steel than the sides,
further enhancing the ability of scattered X-rays to escape and
reach the second detector. Further, shadows created by the
effective illumination from the top (i.e., an image produced from
the detected scatter radiation resembles a photograph that has been
lit from the top) can enhance and better enable the recognition of
objects by using the shadows to highlight three-dimensional
features.
The digital image in FIGS. 11A-11D illustrate the abilities of such
an embodiment. Specifically, these FIGS. 11B-11D were produced
using the second detector to enhance the image of a propane tank
1001 in the trunk 102 of a car, as shown in the photograph in FIG.
11A. Propane tanks in general, and most threats deep within car
trunks, are considered challenges for standard backscatter
imaging.
The shadowing effects discussed above can be further exploited by
processing the signal from the first detector and the signal from
the second detector separately, for example in separate electronic
channels, because each channel will contain different shadow
information.
For example, consider an appearance of the propane tank 1101 in an
image 1102B generated only from scattered radiation detected by the
first detector 1002, as shown in FIG. 11B. In this image, the
propane tank 1101 is essentially discernible.
Next, consider the appearance of the propane tank 1101 in an image
1102C generated only from scattered radiation detected by the
second detector 1005 deployed in the awning position 1005A, as
shown in FIG. 11C. Here, the propane tank 1101 is more readily
discernible than in an image generated from data captured by the
first detector alone. As such, processing the signals from the
first detector and second detector separately yields to a system
operator two distinct views of the target, one of which (in this
case, the image in FIG. 11B) provides a better view of the
target.
Further, compare the appearance of the propane tank 1101 in an
image generated from scattered radiation detected by the first
detector 1002, and the second detector 1005 deployed in the awning
position 1005A, as shown in FIG. 11D. Here, the image 1102D of the
propane tank has a higher signal-to-noise ratio when both signals
are combined, as compared to the images produced from either
detector alone.
Nevertheless, the image 1102C from the second detector alone in
FIG. 11C shows the strongest shadows at the bottom and side of the
propane tank, which helps the viewer to see it as a distinct 3
dimensional object within the trunk of the car.
In practice, perhaps the simplest implementation would allow an
operator or an image analyst to push a button to display either the
combined image, or the separate first detector (which may be
referred to as a "side" detector in this embodiment) or second
detector (awning detector) images. For operators willing to spend
more time manipulating the image, a knob or software slider bar
could be used to produce a compound image by dynamically vary the
mixing ratio from, for example, 100% side, 0% awning, to an equal
mix of both, to 100% awning, 0% side. Producing an image by moving
such a slider back and forth, and thereby dynamically changing the
shadows in the image, could assist in detecting different objects
hidden within a target vehicle.
Accordingly, the embodiments of FIG. 10 provide a number of
potential benefits. For example, signals from the first and second
detector, which may be at varying angles with respect to each
other, may be processed independently, separately from one another,
or may be aggregated. Further, images may be produced, based on the
data from either or both of the first and second detectors. Such
images may be static, or may be dynamically variable based on the
contribution to a produced image from each detector. In addition,
although use of the second detector, which is movable relative to
the first detector, varies the size of the detector array, rather
than merely changing its geometry or shape.
FIG. 10 also schematically another embodiment, including a third
detector 1010, which may be referred to as an "auxiliary" detector
or a "skirt" detector. The third detector 1010 is manually mounted
to, and manually removable from, the vehicle 1000, and extends or
supplements a detector array, such as first detector 1002 for
example. Although third detector 1010 is located at the bottom of
the vehicle 1010, and is may therefore also be known as a "skirt"
detector, a detector array might also be extended by manually
providing additional detectors around the periphery of an existing
array (e.g., first detector 1002). For example, similar detectors
could be mounted to the outside of the vehicle 1000 on the left or
right side of the standard array. Such auxiliary detectors could be
removed and stowed inside the vehicle as desire, for example for
travel at speeds above the usual scan speeds or when the vehicle
1000 is left unattended.
A method for inspecting an object with backscatter radiation is
schematically illustrated by the flowchart in FIG. 12. Step 1201
includes providing a system with at least two detectors of
backscatter radiation, where a least one of the detectors is
movable and can be oriented or re-oriented relative to another
detector, such as in several of the embodiments described above.
Step 1202 then includes configuring the detectors to form a
detector array as desired by the system's operator.
Next, the object is illuminated by a radiation source, and
scattered radiation is detected at step 1203. Finally, data
representing the detected radiation is processed at step 1204 to,
for example, produce an image of the inspected object. The data may
be processed in aggregate form, or separately, as described
above.
Although various embodiments described above are described from the
perspective of configuring an array, other embodiments may also be
described. As noted above in connection with FIG. 1, one potential
benefit of a variable geometry array that the array can be
configured to be compact, thereby allowing the array to be moved
closer to the object to be interrogated, and to maneuver into
spaces that would not allow a larger array to approach.
For example, in FIG. 1, consider a situation in which an operator
of a backscatter detector system desires to interrogate the
aircraft 103 at the corner 110 formed by the wing 108 and fuselage
109. The detector array 110 is too wide to allow system 101 to
maneuver into the tight space between the wing 108 and fuselage
109. However, the array of detectors 106 and 107 on system 102 are
configured to that the size of the array is not as wide, and so
system 102 can easily move into the between the wing 108 and
fuselage 109.
In the embodiment of FIG. 1, both systems 101, 102 are on moveable
bases, or conveyances. For example, systems 101 and 102 may include
wheels or tracks, for example, that allow the systems 101, 102 to
move along at least one line of travel. In the embodiment of FIG.
1, system 101 has a line of travel as indicated by arrow 111, and
system 102 has a line of travel as indicated by arrow 112.
When viewed from a point on line of travel 111, the array 110 of
system 101 presents a certain solid angle. In contrast, if the
array 110 of system 101 were reconfigured into the configuration
illustrated for system 102, then the array 110 would, from that
same point, present a smaller solid angle. In this embodiment, such
a smaller solid angle is a consequence of having reduced the size,
and specifically in this case, the width of the array 110.
This allows a movable system, such as system 102, to advance a
detector array along a line of travel, so as to allow the system to
maneuver in tight spaces. In particular, as the system 102 moves
towards the aircraft 103, the detectors do not form a wide array
that might contact a portion of the aircraft, or any other nearby
object, and thus prevent the system 102 from approaching the
aircraft.
A system, such as systems 101 and 102, may include variable
geometry arrays, including but not limited to the arrays described
herein. Such a system may be described as a variable geometry
backscatter inspection system for inspecting a surface of an
object, including a conveyance configured to move along a line of
travel, a source of a pencil beam of penetrating radiation, the
source coupled to the conveyance and having an axis of emission.
The system has variable geometry detector array that includes a
first and second detector. The first detector has a first alignment
vector, and is coupled to the conveyance such that the first
alignment vector is parallel to, or capable of being configured
parallel to, the line of travel. The second detector also has an
alignment vector. The second detector is movably coupled to the
conveyance, such that the second detector is movable between a
first position and a second position, and when in the first
position its alignment vector is parallel to the line of travel. As
such, when viewed from a point on the line of travel, the array
presents a first solid angle when the second detector is in the
first position and a smaller solid angle when the second detector
is in the second position.
In other words, from the perspective of a person standing on the
line of travel, the approaching system can present an array of one
size when the second detector is in a first position, and present
an array of a smaller size when the second detector is in another
position. For example, but without limitation, such a system may
have variable geometry arrays as schematically illustrated in FIG.
3, FIG. 4A, FIG. 4B, FIG. 5, FIG. 6, FIG. 7A, FIG. 7B, or FIG. 8,
so name but a few.
Indeed, as seen in those figures, the size of the array can be
substantially reduced. In the embodiment of FIG. 3, for example,
the array includes detectors 303, 304, 305 and 306. The solid angle
of such an array, as seen from a point along the line of travel
when all detectors are facing the same direction, includes is the
combined width of those detectors. However, when detectors 305 and
306 are retracted as schematically illustrated by 305' and 306',
the solid angle presented by the array, and indeed the solid angle
as presented by the conveyance 301 with the array, is reduced by
approximately 40 or 50 percent. Similarly, in the embodiment of
FIG. 5, the array formed by detectors 505-508, along with their
unenumerated counterparts on the other side of the conveyance 504,
is substantially smaller when those detectors are refracted in
their clamshell orientation than when they are in an open position.
Indeed, in this way the solid angle presented by the conveyance 504
and array in this embodiment may be reduced by approximately 60
percent. In some embodiments, the solid angle formed by the
conveyance and array of detectors may be reduced to the solid angle
presented by the conveyance alone, as schematically illustrated in
FIG. 7A, for example. Although various embodiments are described in
terms of the relative positioning of alignment vectors, the scope
of embodiments are not limited to arrays in which the alignment
vectors of all detectors are parallel to each other, or to a line
of travel, when in the open position.
Such systems may be distinguished from other mobile systems that
have detectors or detector arrays disposed such that their
alignment vectors are not oriented along the direction in which the
mobile system travels. For example, a truck may have a detector (or
detector array) disposed on the side of a truck, but the truck
could not advance the detector in the direction of the detector's
alignment vector, because a truck cannot move sideways.
A number of embodiments may be additionally described, including
for example a first embodiment of a variable geometry backscatter
inspection system, which includes a conveyance and a source of
pencil beam penetrating radiation coupled to the conveyance. A
primary detector characterized by an alignment vector is coupled to
the conveyance in a first location relative to the radiation
source. A secondary radiation detector characterized by a second
alignment vector is coupled to the conveyance by a movable member
which is movably coupled to the conveyance. As such, the alignment
vector of the secondary detector is adapted for reorientation with
respect to the alignment vector of the primary detector in such a
manner that the sensitivity of the system to radiation scattered
from the object is substantially maximized when the first and
second alignment vectors are substantially parallel. In some
embodiments, the movable member includes an arm with one end
rotatably attached to the conveyance, and the other end coupled to
the secondary radiation detector, such that the arm is rotatable
between an open position in which the second alignment vector is
parallel to the first alignment vector, and a retracted position in
which the second alignment vector is not parallel to the first
alignment vector. In alternate embodiments, the secondary detector
include a first detector unit and a second detector unit the second
detector unit foldable to face the first detector unit. In other
embodiments, the secondary detector is coupled to the conveyance
via a slidable frame, so that the secondary detector may be moved
by sliding the frame parallel to the ground, perpendicular to the
ground, or diagonally relative to the ground.
A variable geometry backscatter inspection system has a source of a
pencil beam of penetrating radiation coupled to a conveyance. A
first radiation detector has a first alignment vector and is
rotatably coupled to the conveyance at a location fixed relative to
the radiation source, such that the first detector rotatable
between a first position and a second position. A second detector
is coupled to the conveyance and has a second alignment vector, the
second alignment vector parallel to the first alignment vector when
the first detector is in the first position. In an alternate
embodiment, the conveyance also has a lift assembly coupled to the
radiation source, such that the lift assembly is extendable to
raise the radiation source above the conveyance.
A method for inspecting an object includes scanning the object with
penetrating radiation generated by a source disposed upon a
conveyance, and detecting penetrating radiation scattered by the
object onto a primary detector characterized by a first alignment
vector coupled to the conveyance, and a secondary detector
characterized by a second alignment vector and movable between a
first position in which the second alignment vector is parallel to
the first alignment vector, and a second position, wherein the
sensitivity of the secondary detector to radiation scattered from
the object is substantially maximized when the first and second
alignment vectors are substantially parallel, and moving the
secondary detector between the first position and the second
position. In some embodiments, moving the secondary detector
involves includes moving the secondary detector from the first
position to the second position, while in other embodiments moving
the secondary detector includes moving the secondary detector from
the second position to the first position. Some embodiments
digitize the backscatter radiation impinging on the secondary
detector in a data acquisition channel during the course of
inspection, and disable the data acquisition channel during the
course of moving the secondary detector out of the first position.
In some embodiments, disabling the data acquisition channel
includes electrically disconnecting the data acquisition
channel.
In addition, the foregoing disclosure can support a number of
potential claims, such as those listed below.
P1. A variable geometry backscatter inspection system
comprising:
a conveyance; a source of a pencil beam of penetrating radiation,
the source rotatably coupled to the conveyance; a first detector
rotatably coupled to the conveyance, the first detector having a
fixed location relative to the radiation source and a first
alignment vector, the first detector rotatable between a first
position and a second position; and a second detector coupled to
the conveyance and having a second alignment vector, the second
alignment vector parallel to the first alignment vector when the
first detector is in the first position.
P2. The variable geometry backscatter inspection system of
potential claim P1, the conveyance further comprising a lift
assembly coupled to the radiation source, whereby the lift assembly
is extendable to raise the radiation source above the
conveyance.
P3. A method for inspecting an object, the method comprising:
scanning the object with penetrating radiation generated by a
source disposed upon a conveyance; detecting penetrating radiation
scattered by the object onto a primary detector coupled to the
conveyance, the primary detector characterized by a first alignment
vector; detecting penetrating radiation scattered by the object
onto a secondary detector, the secondary detector characterized by
a second alignment vector and movable between a first position in
which the second alignment vector is parallel to the first
alignment vector, and a second position, wherein the sensitivity of
the secondary detector to radiation scattered from the object is
substantially maximized when the first and second alignment vectors
are substantially parallel; and moving the secondary detector
between the first position and the second position.
P4. The method for inspecting an object of potential claim 3,
wherein moving the secondary detector comprises moving the
secondary detector from the first position to the second
position.
P5. The method for inspecting an object of claim potential claim 3,
wherein moving the secondary detector comprises moving the
secondary detector from the second position to the first
position.
P6. The method for inspecting an object of claim potential claim 3,
further comprising digitizing the backscatter radiation impinging
on the secondary detector in a data acquisition channel during the
course of inspection and disabling the data acquisition channel
during the course of moving the secondary detector out of the first
position.
P7. The method of inspecting an object of potential claim 6 wherein
disabling the data acquisition channel comprises electrically
disconnecting the data acquisition channel.
The embodiments of the invention described above are intended to be
merely exemplary; numerous variations and modifications will be
apparent to those skilled in the art. All such variations and
modifications are intended to be within the scope of the present
invention as defined in any appended claims.
Various embodiments of the invention may be implemented at least in
part in any conventional computer programming language. For
example, some embodiments may be implemented in a procedural
programming language (e.g., "C"), or in an object oriented
programming language (e.g., "C++"). Other embodiments of the
invention may be implemented as preprogrammed hardware elements
(e.g., application specific integrated circuits, FPGAs, and digital
signal processors), or other related components.
In an alternative embodiment, the disclosed apparatus and methods
may be implemented as a computer program product for use with a
computer system. Such implementation may include a series of
computer instructions fixed either on a tangible medium, such as a
non-transient computer readable medium (e.g., a diskette, CD-ROM,
ROM, or fixed disk). The series of computer instructions can embody
all or part of the functionality previously described herein with
respect to the system.
Those skilled in the art should appreciate that such computer
instructions can be written in a number of programming languages
for use with many computer architectures or operating systems.
Furthermore, such instructions may be stored in any memory device,
such as semiconductor, magnetic, optical or other memory devices,
and may be transmitted using any communications technology, such as
optical, infrared, microwave, or other transmission
technologies.
Among other ways, such a computer program product may be
distributed as a removable medium with accompanying printed or
electronic documentation (e.g., shrink wrapped software), preloaded
with a computer system (e.g., on system ROM or fixed disk), or
distributed from a server or electronic bulletin board over the
network (e.g., the Internet or World Wide Web). Of course, some
embodiments of the invention may be implemented as a combination of
both software (e.g., a computer program product) and hardware.
Still other embodiments of the invention are implemented as
entirely hardware, or entirely software.
* * * * *